Bracing systems serve a number of important roles in bridges. Braces provide stability to the primary girders as well as improving the lateral or torsional stiffness and strength of the bridge system both during construction and in service. One type of bracing is top or bottom lateral bracing (a relative brace system), which may be needed as temporary bracing during construction. In steel I-beam or I-girder bridges, lateral bracing generally is placed either in or near the plane of the flange being braced. The lateral bracing helps to prevent lateral movement of the structural system during construction. Flange level lateral bracing may also be needed in deck replacement projects on long span bridges. In the final condition, the concrete deck can typically resist lateral wind loads and prevent significant horizontal movement of the structure. However, if the deck requires replacement and is removed, lateral deflections can be excessive in long span bridges without lateral bracing. Essentially, a lateral bracing system will stiffen a structure significantly, as compared to one without any lateral bracing.